I know there is a few things I need up upgrade to go from a 75hp shot to a 125hp shot on my Zex kit. I know I need a new fuel pressure regulator, fuel pump, and a tune. Do I need bigger fuel injectors? Does anyone know the part numbers for the fuel pressure regulator and the fuel pump that I will need to run the 125hp shot.

An Aeromotive or BBK regulator should work fine. I've used both. The ZEX kit is set -up for the stock 19 lb injectors and the stock motor and 93 Octane fuel. But safer is better !. I'm also assuming this is a DRY KIT?

I ran everything from 55 up to 125 HP Shot on my stocker for years with no problems. I pulled the factory stock shortblock out with 116K miles on it with no problems when I put the other stock motor in with the PI/bullitt stuff. I'm still running the 125 shot on it. It can be done if you monitor what you are doing.